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So I got the top windshield trim off this evening to check the birdcage condition. It is in amazing condition for 49 years old, at least 15 or so of those years sitting outside.
So my question is, what is the best way to preserve this and keep it solid for the next 50 years? Grind the rusted areas clean and paint with the zinc chromate? Toss some por-15 on it and call it good?
Also there was a bunch of putty type material packed into the corners. Should I replace this material and if so, what is it?
I once looked up "putty" using the factory assembly manual and the web. It was listed as something along the line of "gunnable fibered black bitumen". That specific GM product is no longer available but what is amounts to is a caulk gun tube of fibered roofing tar. The same stuff is used to seal all of the "T" trim pieces and the exterior side windshield moldings.
Zinc chromate is garbage compared to modern epoxy and urethane primers. It obviously didn't work on most Corvettes. Besides, it primary application was on aircraft aluminum, not steel. I suggest a good two part epoxy primer.
Last edited by Shovels and Vettes; Aug 17, 2017 at 05:44 PM.
Are you taking the glass out , hinges off as well ? If yes I would sand blast it spotlessly clean and then use modern paints to seal it and prime it . any grit that gets inside the metal frame will end up down in the no. 2 mount areas .Down side to this is its messy and you have to have a good size compressor to hit it hard enough to clean properly and get the proper PPE so it doesn't poison you
Or spend hours with a wire wheel , you will get an OK result with the wheel(s),it will be doable in your shed . You can then rely on the modern rust paints (POR) to protect what you have done before top coating .
Both methods can damage the fibreglass edges as well , but the blasting can get into the tighter corners a bit better .
Your first pic looks like the green (original ) paint has pooled in the top right corner ? nice
When I get to that point I will scrape off what I can , sandblast clean and then put por -15 on it ! Check back with me in about a 100 years and I'll let you know how it's holding up !
But , just like someone else said there are a lot of good epoxy primers out there and with all the good stuff to choose from I would only use zinc chromate if a customer insisted on it. JMHO
On my '68 coupe I just cleaned it good with a wire brush and a solvent. It didn't have any scale or flaking. After cleaning I used POR15 on it. These cars will not likely ever be sitting outside in the weather again. I removed the windshield because I had seen what some of these cars can look like in that area and was a bit paranoid. With access like that you can clean it pretty good. If blasting is practical it certainly wouldn't hurt. In my case I didn't think it was worth the effort.
Thanks everyone for the replies and thoughts on the subject. I do not plan on pulling the windshield, at least at this point. The frame really looks much better than I was expecting so I really don't want to open that can of worms.
I think my plan of action will be to wire brush the frame clean and coat it in either POR-15 or a 2 part epoxy paint. I am not going for NCRS original so I don't care if it has the green zinc chromate color or not lol.
Hi,
I'd be concerned with using POR15 on the windshield frame.
It's well documented that many finishes don't adhere well to POR15.
Windshield installation instructions are quite explicit about the finish that is applied as a top coat to the windshield frame to insure the proper bond between the windshield seal used and the finish on the frame.
Regards,
Alan
Zinc Chromate Primer from an aircraft maintenance supply company, (so it actually has the chromate in it), and then a black semi-flat finish.
We replied at almost the same time so I hadn't seen your post yet.
That would definitely be a concern if I were pulling the windshield. I really don't want to do that at the moment and just want to preserve what I currently have.
If you have no leaks around the glass and the windshield is still in good condition, I HIGHLY recommend that you leave it alone and just do preservation work inside the frame. Be careful not to put any pressure/loading on the windshield while you do that work, as the 40 year-old glass becomes very brittle and will easily crack.
Wire brush all of the loose debris and rust/corrosion out of that area. I see nothing wrong with using zinc chromate (or self-etching primer) on metal surfaces, as long as you let it dry completely before sealing that area.
Bitumin is antiquated for sealing that stuff up. You want to find a good quality butyl rubber caulking material (Lowe's no longer sell it) to seal it up well. Butyl will never harden; it cures to a flexible substance that can flex with temp and humidity changes; it is incredibly sticky stuff and seals really well for many, many years.
Whatever you do, do NOT seal that up with some chinzy silicone caulk.
On my '68 coupe I just cleaned it good with a wire brush and a solvent. It didn't have any scale or flaking. After cleaning I used POR15 on it. These cars will not likely ever be sitting outside in the weather again. I removed the windshield because I had seen what some of these cars can look like in that area and was a bit paranoid. With access like that you can clean it pretty good. If blasting is practical it certainly wouldn't hurt. In my case I didn't think it was worth the effort.
I'm going to correct myself on this post. I did this step a number of years ago and now that I think about it (and look at my own pic), that is clearly not POR15 which I have only used in brush form. That is an Eastwood product of some type that I sprayed on after cleaning. I agree with someone who advised highly about removing the windshield. If it is tight and sealed then leave it alone, especially based on the visible condition of your frame. I probably should have left mine alone in retrospect but I did have one professionally installed and he did an excellent job.
Hey Chuck, the only thing I can add is to take your time and don't do anything to aggressive. I have always had good success with various wire wheels. Slow but safe!You could you use the 2 part epoxy and then for aesthetics do the zinc chromate. The car is to important to you to go all out ballistic.
Just saying!
RVZIO
Thanks everyone. I will wire wheel it and use a 2 part epoxy. I am not a stickler for originality so I don't need the the zinc chromate appearance. I will definitely be careful because I don't want my windshield cracked. It still has the 25th anniversary NCCC convention road race participant sticker on it.
Alright, so I have one other question/thought on this. I am thinking about drilling an access hole in each a-pillar to allow me to get an Eastwood internal frame paint nozzle into the boxed in portion of the top windshield frame. There are only a few screw hole in it and I don't think the nozzles would fit in them. I think added this coating while I'm working on that area already would make sense. The holes would be covered and not visible when the trim is installed.
Considering the [good] condition of the outer birdcage members, I believe doing that would be a waste of time. Also, any stress / vibration you put into the windshield frame has some risk of damaging the windshield.
That being said, if you really want to do that, now is the time.
Considering the [good] condition of the outer birdcage members, I believe doing that would be a waste of time. Also, any stress / vibration you put into the windshield frame has some risk of damaging the windshield.
That being said, if you really want to do that, now is the time.
Probably true. My main thought was that the car has been in the family for 45 years and I'd like it to be in the family for another 45.
Windshield preservation questions
